At that price point pickings start to get slim.
A case is such a subjective thing it's tough to help.
If you can live without a window check this out.
https://www.newegg.com/Product/Product.aspx?Item=N82E16811129197
So i want to spend less than £45, approx $55, on a case with support for a MicroATX MOBO. My requirwments are at least 1x USB 3 header and A window (i.e. not 2). I found these three: Cooler Master - MasterBox Lite 5 ATX Mid Tower Case, Realan E-D3 Micro ATX case, Corsair - 100R ATX Mid Tower Case
Does anyone have anything to say about anything, things i should know about, good/bad experiences? Should i look at different cases? Thanks a bunch!

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